We do not have the right to order people to act in ways of which they are incapable, such as commanding them to forgive. The justice and revenge impulses are strong in us and seem to be intrinsic to our humanity. Even if we can identify many situations in history where these impulses have trapped people in unending spirals of revenge, we ought to acknowledge that a primitive kind of moral coherence is in operation there that we should not be too quick to condemn, particularly if we have never lived in similar situations.
Robert Holloway describes what constitutes forgiveness, and while he recognises both that revenge can trap one in the past and that forgiveness is an intrinsic good, he acknowledges that it is not always easy (or perhaps even appropriate) to forgive and suggests that there are times when magnanimity towards those who have wronged us may suffice.